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• <br />• <br />Tp..l~r..l.[I....r..• [.II..W <br />en-en..r ..... e.nanul <br />eV-sn..r ........u[a <br />R -Rybl~~ 00 <br />F -CUInuUn.m <br />T -Tniu.WU .h.[[bn a oun.pn[ <br />R -flNhl ~In[[bn .f .u[u.m.nt <br />V -V.r[I[.I ~Y.[[I.n .r n... W.4nt <br />l <br /> <br />Figure 2 -Types of Ground Motion Waves <br />Since the 1920's or earlier, ground vibrations have <br />been studied extensively to determine their <br />potential for damage to various structures and <br />construction materials. Blasting activities aze <br />among the most common sotuces of ground <br />motion, have therefore been studied the most, and <br />have thus prompted the ordinances and regulations <br />that are in place. At the present time, the only <br />federal regulation that pertains to ground motion is <br />from the Office of Sttrface Mining and <br />Reclamation Enforcement (OSMRE). This <br />regulation was written to protect residential <br />structures. Complaints of damage to residences <br />were, and aze, the most common form of <br />complaint resulting from the perception of ground <br />motion. Colorado Division of Minerals and <br />Geology ground motion and air overpressure <br />regulations mitror the federal regulations. <br />Scaled Distance (SD) is a method by which results from differently sized chazges may be <br />normalized and compared. SD = D/,~, where D is the surface distance in feet from the nearest <br />drill hole collar to the recorder and W is the maximum charge weight per 8 millisecond delay <br />period in pounds. <br />The ground motion attenuation study is designed to statistically predict safe surface standoff <br />distances from residences, water wells, swimming pools, and other points of concern. Particle <br />velocity data acquired in the field are input into a least squares linear regression analysis program. <br />The United States Office of Surface Mining and Reclamation Enforcement (OSMRE) has approved <br />this program. The regression analysis yields asite-specific attenuation formula in the form: <br />PPV = H(SD)-B <br />where, H =the velocity (y axis intercept) at a scaled distance of one, <br />B =the slope of the curve, <br />PPV =the peak particle velocity in inches per second, and <br />SD =scaled distance =distance from shot to recorder divided by the <br />squaze root of the charge weight. <br />• <br />"fhe program also yields the correlation coefficient (goodness of fit), rZ <br />Once the equation for the ground motion is defined, predictions may be made for peak particle <br />velocity, charge weight, or distance by manipulating the equation and by holding two of the <br />variables constant. <br />9 <br />